The Bundesliga leaders have only themselves to blame after Jadon Sancho, in the absence of Dortmund's captain, Marco Reus, took control of Dortmund's game in the first half, firing in for the lead in the 32nd minute and slicing through the hapless Hoffenheim defence at will.
Dortmund hold a seven-point lead in Germany and Bayern Munich's six-year domination of the Bundesliga is under serious threat with Sancho in the thick of things.
After the restart, Hoffenheim came out highly motivated but it were still the hosts who continued scoring as Raphael Guerreiro made the most of Goetze's assist to triple the lead in the 67th minute.
"It was very bitter after a very good first half with Sancho playing an outstanding game", said Dortmund assistant Edin Terzic, standing in for head coach Lucien Favre at the news conference after the Swiss missed the game due to flu.
Hoffenheim didn't give up, however.
Jadon Sancho has disclosed that the tattoo he inked on his left arm is a special tribute in memory of his baby brother who left this world when he was barely five-years-old. Eight minutes later, Pavel Kaderabek grabbed another.
"When you lead 3-0 at home it shouldn't happen".
"We have a clear structure, but you can often look at our team sheet and see how many young players play each Saturday - not just in cup games, but big matches, including the Champions League". In addition, he also scored against Bayer Leverkusen last season.
Reus has enjoyed a superb season, scoring 17 goals in all competitions.
Lewandowski caused an own goal from Jeffrey Bruma in the 11th minute and restored Bayern's lead in the 27th, two minutes after Ahmed Kutucu scored with Schalke's first foray forward.
Serge Gnabry sealed Bayern's win before the hour-mark after Lewandowski inadvertently set him up with a bicycle kick.
Belfodil beat a crowd of defenders to connect with Dennis Geiger's cross and head in an 87th-minute goal that saw Dortmund fail to capitalise on Borussia Monchengladbach's 3-0 loss at home to Hertha Berlin.
Also, Hannover defeated 10-man Nuremberg 2-0 in a bottom-of-the-table match, Frankfurt drew at Leipzig 0-0, and Freiburg drew with Wolfsburg 3-3.
